fuel tank issues

[luis.e30325es]

ok guys,
so the other day i ran out of fuel on the freeway, but my gauge said i had half a tank, i tried filling it, it only took about 20 bucks worth of fuel, usually fills with 50-55.
ever since this happened ive been filling up ever 3 days just so i wont get stranded on my way to work or school.
have any of you had this issue before?
i have a '86 325es.
i looked at a diagram of my tank and fuel sending unit, i think it might be the transfer tube that connects both sides of the tank just below the drive shaft, i may be wrong.

all and any help is appreciated.
thanks

[jlevie]

It sounds like the transfer pump (mounted in the right side of the tank) has failed. But it is possible that the tank is loaded up with rust that has clogged the transfer tube that runs below the drive shaft. Pull the pump and level sensor from the tank and have a look at the bottom of the tank with a pen light while stirring the bottom of the tank with a stick. If there is a layer of rust in the tank, you will see/feel it. Then test the transfer pump to see if it is working and able to pump fuel.

[luis.e30325es]

It sounds like the transfer pump (mounted in the right side of the tank) has failed. But it is possible that the tank is loaded up with rust that has clogged the transfer tube that runs below the drive shaft. Pull the pump and level sensor from the tank and have a look at the bottom of the tank with a pen light while stirring the bottom of the tank with a stick. If there is a layer of rust in the tank, you will see/feel it. Then test the transfer pump to see if it is working and able to pump fuel.

rust in my tank, i dont like how that sounds, sounds harmful to me engine..
i will have to do this this upcoming weekend.
could it be possible that the transfer pump also get stuck? ive had to deal with stuck pumps on other cars (not bmw)
any tips with the transfer tube? i dont want to brake anything that i could avoid breaking by following safe steps.

[jlevie]

First check the tank for rust. If the tank isn't loaded with rust there is little chance of the tube being plugged. And if the tank is loaded with rust, it will have to come out and be replaced or acid cleaned and sealed, at which time you can clear the tube. A worn pump can stick, in which case a rap on the top of the pump may free it. But a worn pump will stick again or just completely fail. Replacement is the only realistic option.

[E30Gus]

Also pull the pump out and look at the filter/screen. That can get nasty and is a good indication that there is crap in your tank. I just finished doing a tank swap after acid cleaning and sealing and I found very little chunks floating around in my original tank which surprised me a bunch. My previous pump failure and fuel starvation issues were due to a clogged transfer tube primarily. If you can get that transfer tube off, then I would check that after looking at the tank and pump. The tube is made of copper I believe and I could not get mine off with out ruining it so be carefull and soak with PB blaster or similar for a while.
Does your external fuel pump buzz? This is an indication that crap is getting to it from the tank.

[Unearth078]

ill leave this here... http://www.e30tech.com/forum/showthread.php?t=28865

[luis.e30325es]

First check the tank for rust. If the tank isn't loaded with rust there is little chance of the tube being plugged. And if the tank is loaded with rust, it will have to come out and be replaced or acid cleaned and sealed, at which time you can clear the tube. A worn pump can stick, in which case a rap on the top of the pump may free it. But a worn pump will stick again or just completely fail. Replacement is the only realistic option.

acid cleaned and sealed?
hopefully this isnt the case.
wish me luck.

Also pull the pump out and look at the filter/screen. That can get nasty and is a good indication that there is crap in your tank. I just finished doing a tank swap after acid cleaning and sealing and I found very little chunks floating around in my original tank which surprised me a bunch. My previous pump failure and fuel starvation issues were due to a clogged transfer tube primarily. If you can get that transfer tube off, then I would check that after looking at the tank and pump. The tube is made of copper I believe and I could not get mine off with out ruining it so be carefull and soak with PB blaster or similar for a while.
Does your external fuel pump buzz? This is an indication that crap is getting to it from the tank.

hopefully it is that tube. yeah on the outside of it, the tube looks like crap, will have to soak it over night and work on it the next day.
and yes the external pump buzz, i was wondering what that was..
this is just getting me worried that the inside of my tank will look like crap.

is acid cleaning and resealing expensive? and i HAVE to take out my tank to do this?

[jlevie]

If the tank is loaded with rust, then it will have to come out of the car. Cleaning and sealing the tank isn't a difficult DIY and can be done for about $60 in materials. If you drop the tank on Friday evening you can put it back in the car Monday evening, worst case. In many cases you'll have the tank cleaned and sealed Saturday evening and can reinstall the tank Sunday evening.